Silicon carbide is expected to be used as a material in the next generation semiconductor device. Silicon carbide has excellent physical properties such as three times the bandgap, ten times the breakdown field strength, and three times the thermal conductivity as compared to silicon. As a result, it is possible to create a semiconductor device which is capable of achieving low power loss while operating at a high temperature using silicon carbide.
As a structure for reducing on-state resistance of a metal oxide semiconductor field effect transistor (MOSFET) manufactured using silicon carbide, there is a trench gate type MOSFET in which a gate electrode is provided in a trench. In order to further reduce on-state resistance in the trench gate type MOSFET, it is preferable to decrease a channel length. However, when the channel length is decreased, undesirable channel leakage current flowing between a drain and a source when the MOSFET is turned off is increased.